In the conventional testing methods for digital-to-analog converters (DAC) and analog-to-digital converters (ADC), an accurate reference voltage must be supplied to the analog signal for comparison, especially in high bit number converters. There is also a stringent requirement in the test voltage and the noise signal of the test machine. This leads to a long test time required and a complicated test procedure. In charge redistribution type DACs and ADCs, the internal circuit is mainly constructed of capacitors and the error and linearity of the converted signal are determined by the internal capacitance ratios. If a converter is tested by an input analog signal, it is not only time consuming but also produces low reliability. It is therefore an important requirement in large volume testing to reduce the test time and to simplify the test procedure.
It is therefore an object of the present invention to provide a test method for charge redistribution type digital-to-analog and analog-to-digital converters to determine the accuracy and linearity of the converted signal.
It is another object of the present invention to provide a test method for charge redistribution type digital-to-analog and analog-to-digital converters by using a capacitance comparison method to compare the capacitance ratios in the converter tested for obtaining the accuracy and linearity of the converted signal.